The Republican presidential candidate also responded to President Obama's criticism of the GOP field and insisted he'll be the party's 2016 nominee.

Appearing in the studio on the ABC morning show, Trump said the retired neurosurgeon who's been challenging him in the polls "just doesn't have the experience" to be president.

"It’s not his thing.… You know, you're born with it. He hasn't got the temperament for it. It's not the right thing for him," Trump told George Stephanopoulos. "I'm going to make the greatest deals you've ever seen on trade. We're going to run the military properly. I'm going to take care of the vets. Ben can't do those things. Ben cannot deal on trade."

Trump also talked about the debates following last week's controversial CNBC face-off, responding to President Obama's criticism of how the GOP candidates handled themselves.

Trump hit back at Obama, saying "He can't handle the country."

"He's doing a terrible job running the country," Trump added. "So he may say the Republicans don't get along on a debate. And it's not us. We’re being asked very rude questions, many of them directed at me…. He cannot handle the country. He is doing a terrible, terrible job."

Trump, who said that he won't join forces with his fellow GOP candidates to negotiate the terms of future debates, also revealed some of his demands for future debates, which are the same as specific requests he made ahead of the CNN and CNBC face-offs.

"I don't think it should be three hours. That's one thing. That was always my demand," Trump said. "And I'd like money …the networks are making a fortune with the debates. I'd like to see the wounded warriors and some of the veterans get some of the profits. Because we're going in, we're getting nothing, and that's fine, but they're getting tremendous ratings."

Beyond that, Trump indicated he doesn't care much about the format of the debates. "I just want to answer the questions and be done with it," he said. "They can ask tough questions. I really don't care."

Trump also took on his other GOP opponents, including Marco Rubio, reiterating his remarks that the senator is "overrated" and "a lightweight."

"I think Putin would eat him alive," the real estate mogul said of his GOP competitor.

Trump also went after Rubio supporter Paul Singer, saying, "You've got to look at that record. You take a look at that record. You take a look at what he stands for."

As for Jeb Bush, Trump said he should "absolutely" drop out.

"He doesn't have a chance," Trump said. "He's got money but the money's not going to do it."

Trump predicted that he would be the GOP nominee and said he thinks Hillary Clinton will be the Democratic nominee "unless she gets indicted."

But if he doesn't become president, Trump said he won't have to worry about the politicians he's facing now.

"When this is over, if I win, great, I'm going to make the country great again," he said. "If I lose, fine. That's fine. I'm not going to deal with these people. That's it. I go into the sunset...and I build buildings."